I would first see if there are property managers to manage it. If not, I personally would not take a property in a rough neighborhood. It's worth paying extra for the peace of mind and future appreciation. Good luck!

In a rough neighborhood I would never bank on 10% vacancy... you'll have much higher turn over and greater costs with rent readies between tenants... I'd bump it closer to 25% to account for likely having to fill it twice a year and down time as you fix it back up each time. Those are definitely units you'll want to try to bullet proof to lessen the impact of rough tenants and you may have to redefine in your mind what "rent ready" means.

Good tenants don't live in rough areas no matter how nice the unit is...

That said, there is money to be made... if it's the PM's headache and not yours, financially it might make sense. Obviously there'll be more up and down on the units (less steady cash flow) that you'll have to prepare for (or have the PM hold larger reserves for you) but there's a lot of people doing very well off that lower caste.